The present invention relates in general to building panels, and, more particularly, to means for punching composite building panels.
A reinforced insulated concrete building panel is disclosed in U.S. Pat. No. 4,117,639. This panel has a plurality of layers, including a layer of insulation sandwiched between inner and outer layers of concrete. Shear connectors are embedded in the panel to prevent delamination of the panel.
These shear connectors are U-shaped and have bent lowermost ends which extend at approximately right angles to the axes of the legs. The lowermost ends help to securely set the shear connector in the panel.
The shear connector should be placed in an easy manner, and in a manner which reduces the possibility of mistakes and neatly places the shear connectors while avoiding a possibility of damaging the insulation. Heretofore, placing these shear connectors has been extremely difficult in some of the thick and/or heavy density materials.
There are known methods of placing shear connectors. For example, in early panels shear connectors of various types were installed at the joints between sheets of insulation. However, this method requires that a space be defined between the insulation layers. Furthermore, using such a method, the insulation joints were required to be in a special pattern to suit the spacing of the shear connectors.
Another known method of setting shear connectors includes merely pushing the shear connectors through the insulation as required. While this method may be satisfactory on soft insulations, it is not satisfactory on the better class and heavier density insulation for a number of reasons. These reasons include: (1) It is very difficult to push a shear connector through even two inch thick insulation. Furthermore, due to the density of the insulation, there is a tendency for a large piece of insulation to break off as the shear connector is pushed through. (2) If insulation breaks off, a broken piece may be pushed into the wet concrete below and leave a void in the insulation. Such a void affects the thermal performance of the finished product.
Pre-punching insulation at the factory to a predetermined grid may be another way to solve the above problems. However, pre-punching insulation is not practical for the following reasons: (1) The spacing or grid can change from day to day or even in the same cast of panels, as the spacing changes according to the length of the panels. (2) The spacing of the shear connectors is different at the top and bottom of the panels for structural reasons. (3) Special sheets of insulation may be required to complete the length of each panel.
Accordingly, there is need for a device which sets shear connectors, especially shear connectors such as disclosed in U.S. Pat. No. 4,117,639, in an easy, accurate manner without damaging the insulation or endangering the shear connector or the thermal performance of the panel.